Abstract

The National Institute of Public Health and the Environment (RIVM) evaluated the Chlamydia Screening Implementation (CSI), a large scale programme offering annual screening to more than 300,000 young people in Amsterdam, Rotterdam and South-Limburg. This was the first time such a large group of young people was invited to get tested for STI in the Netherlands. Testing and treating for Chlamydia at large scale aims to bring down the transmission. This trial implementation was set-up to evaluate whether the screening programme was feasible, effective to bring down the prevalence of infections and cost effective. On the basis of this evaluation, the Minister of Health will decide upon a national roll-out of screening. In anticipation of this decision, the program will continue for one year, also enabling further data collection.

The percentage of young people that participated was lower than expected from the start (one out of eight participated) and decreased in subsequent rounds. In the first round 4.2% of participants tested positive for Chlamydia and this decreased to 3.5% in the third year. Predictive modeling showed that screening for ten years will only lead to a small decline in Chlamydia prevalence. If participation rates decrease further, the prevalence will go back towards baseline levels under regular STI-care. The screening is unlikely to be cost effective.

Invitees received a letter explaining how to request a testkit via the internet and send a sample to the laboratory. The programme proved to be technically feasible and participants were enthusiastic about the set-up. 'High-risk-groups' such as young people under 20 years, of non- Dutch ethnic background or from high-risk areas, were less likely to participate, but were more likely to test positive. Questionnaire surveys showed that non-responders often had a plausible reason not to participate (not yet sexually active, not been at risk, tested recently). Participants reported more frequently higher risk sexual behaviour.